Once you know what Pokémon you want to enter into the exchange, you will use its Options dropdown and choose "Secret Santa Exchange" under the "Move to" option.

The exchange itself will happen after 11:55pm on December 25th, meaning you have the full weekend to deposit something. Depending on my availability, it will likely be hours later, or the next afternoon, but the ability to deposit will be disabled closer to reset.

Some reminders (and notes for newcomers):

You can only enter ONE Pokémon in the exchange and you will not be able to undo your choice.

The Pokémon will immediately be converted into an egg of its BASE form, again meaning you cannot undo your choice.

When the exchange runs on reset of Christmas Day (December 25th), your Pokémon's egg will be given to someone else, and you will receive an egg from another person OF EQUAL RARITY.

Rarity is dex rarity, not how "rare" you perceive it to be by availability on the site.

Rarity is by BASE rarity. This means submitting certain novelties, such as a MEGA or some other Novelty evolution, will likely have a NON-NOVELTY base rarity (Common, Uncommon, Rare). A Mega Charizard would be a regular Charmander. Snowman Froakie would be a regular Froakie. A Winter Vulpix, however, would be considered a Novelty and would be given as a Winter Vulpix egg.

Manaphy/Phione have been disabled this year, but summonable legendaries are in their own rarity grouping, rather than with all legendaries (Very Rare). This means submitting a Ho-oh, Lugia, etc, will get you an equivalent summonable legendary back; you will not get something like an Articuno.

Submitting a SHINY means you will get a shiny in return, of equal rarity.

THERE ARE NO GUARANTEES THAT YOU WILL GET WHAT YOU WANT, NOR THAT YOU WILL EVEN GET SOMETHING THAT YOU DO NOT ALREADY HAVE (although giving you something not already in your dex is the primary objective, but depending on how many people enter, and which Pokémon are entered, and how full your dex is, this may not have a 100% success rate)

YOUR PARTY LIMIT WILL BE DECREASED TO 5 UNTIL THE EVENT ENDS, TO ENSURE YOU HAVE A SPOT OPEN IN YOUR PARTY FOR YOUR NEW EGG. Keep this in mind in case you want to wait until the 25th to deposit your Pokémon.

You cannot submit an Arceus, Manaphy, Phione, nor a Black/White Kyurem. Those are the only restrictions.

The exchange script will prioritize users based on their December 25th activity — those who were more active that day will be first to get an exchange Pokémon, which helps ensure they get something new.

I might not be available precisely at reset on the 25th, which means the actual exchange will take place later that night if not the next afternoon. Just an FYI.

I will open this thread for replies after the actual exchange happens.

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Want a rotating avatar like mine? Check out my website: randimg!Thanks to all of the people in this thread and this thread for the various avatars!

I used a Blue Stone on my Zerxeres to corrupt. I know the Zerxeres would have been shiny (wonder who got my Dracowymsy?), but I'm not sure that it will be shiny when corrupted. Still, it's worth a shot.

It means that releasing corruptable pokemon - even common ones - is worthwhile.